As a matte clear coating composition to be applied to an aluminum member, a clear coating composition containing silica fine particles as a matting agent has widely been known.
In a general use environment, an aluminum member, such as an aluminum wheel, is subjected to washing or the like for the purpose of cleaning. During the cleaning, the aluminum member is often wiped with a cloth or the like.
However, such wiping using a cloth or the like has been problematic in terms of the abrasion load applied to the coating surface; as a result, the gloss in the abraded portion increases compared with the original matte state (the glossiness increases). Such a defect more significantly occurs when a hard contaminant, such as brake dust is attached to an aluminum wheel of an automobile or the like.
As an example of an aluminum material made of a matte-coated aluminum base material, Patent Document 1 discloses a satin-touch aluminum material in which an effect coating film formed of a coating composition containing an effect pigment, and a coating film with a dried coating film thickness of 10 to 50 μm formed of a clear coating composition containing 5 to 60 parts by mass of spherical resin microparticles with an average particle size d50 of 10 to 50 μm per 100 parts by mass of coating-film-forming resin solids content are sequentially formed on an aluminum base material.